Wire rope lubricant



te States No Drawing. Filed May 11, 1961, Ser. No. 109,262 8 Claims.(Cl. 252-55) This invention relates to compositions comprisingpetrolatum and oxidized asphalt which are suitable for use as wire ropelubricants.

Wire rope requires lubrication of the strands and wires of which it iscomposed since in operation there will be considerable motion betweentheir surfaces. For instance, an elevator cable which runs pulley wheelsor drums is subjected to constant bending and flexing. In the operationof outdoor equipment such as a yard crane or a dragline in earth moving,the lubricant should not only prevent rubhing wear between the strandsbut must also protect the strands and wires against rust or corrosion.

Wire rope, e.g., cable, is widely used in materialshandling work. Thisincludes high lift service, pulling operations, short lift work, andlong haul work. The elevator and the mine hoist are examples of highlift service. Pulling operations include the dragline, excavatingmachine, dredge, and car puller. Short lift work, in turn, isexemplified by the yard or traveling crane, and long haul work by thesuspension and moving cables used in cable cars and ski lifts.

An industrial wire rope lubricant must be able to operate satisfactorilyin extremes dictated by the particular use, climate and location. Thus,there can be extreme variations in temperature as, for instance, in asteel mill crane which handles hot ingot molds or equipment which mustbe used in a desert or artic type climate. The particular use mightentail high pressures between strands and wires. Such a situation mightcome about when the rope has -to work over small diameter drums orsheaves. Work of this type involves continuous bending and straighteningout of the rope. In many instances, wire rope will be subjected tocontaminants such as water, acids, acid fumes, dirt, and dust. Thesecontaminants are especially present in outdoor service or aroundindustrial plants where there can be chemical fumes and the like.

Many Wire ropes are manufactured by winding the metal strands around afiber core or another smaller wire core. The core aids in providingstrength and resistance to pressure Where the requirements for stretchand elasticity are not too exacting. A Wire cord is used where the ropemay be subject to temperatures which would be nigh enough to char afiber core. In normal temperature service the fiber core serves not onlyas a strand support but also as a lubrication aid because it becomes areservoir for reserve lubricant when the latter is able to penetrate therope structure completely. Under such conditions the lubricant, in turn,serves as a fiber core preservative in the prevention of bacterialreact-ions. A well lubricated core also provides assurance that theinnermost wires will be protected against rusting and abnormal Wear. Anotherwise dry core could absorb moisture and promote corrosion withinthe rope.

A good lubricant must be able to provide protection against theseconditions. Other Wire rope lubricant characteristics which can be ofsignificance include the ability to (1) resist melting and running offat high storage and operating temperatures, (2) resist cracking andsplitting in cold Weather, *(3) be sufficiently tacky to resist drippingand flying off, (4) repel water and resist emulsification, (5) resistcollecting dust and dirt, (6) resist removal from the rope by the actionof the elements, and (7) not be affected by acid, salt water, acidfumes, or other industrial pollutants. Although any or all of theseproperties can be of importance depending on the particular use,probably the most important is the first one.

It has now been discovered and forms the substance of this inventionthat compositions can be prepared which have outstanding utility as wirerope lubricants. These lubricants are of the solid or greaselike type.In this type of wire lubricant it is important that there be obtained acertain relationship between penetration values and softening pointvalues. The penetration values referred to herein are needle penetrationvalues at 77 F. unless otherwise designated. By softening point is meantthe temperature at which the composition tends to become liquid.Penetration is the term used to designate the relative hardness of thecomposition. Thus, on a relative scale, a low penetration figure meansthat the composition is relatively hard and a high penetration valuemeans that the composition is relatively soft. The softening point isthe most critical factor since a good wire rope lubricant must be ableto Withstand melting and running off in wide extremes of all climaticand environmental temperatures. Thus, an outstanding wire lubricantwould be equally eflicacious in a hot desert environment as well as acold snow and ice environment. A relatively high softening point insuresthat the lubricant will not melt and run off the wire rope underextremely hot conditions and a relatively high penetration valueaccompanying this softening point value insures that the lubricatingcomposition Will not become brittle with a tendency to chip or break atVery cold temperatures.

It has been known in the art to use either petrolatum or asphalt basedcompounds as wire rope lubricants. It has now been discovered that whenfrom about 1 to 15, eg 7 to -12, wt. percent of a petrolatum having asoftening point of from 120 to 175 F, e.g. 140 to 175 F., and apenetration value of from to 120, e.g. 80 to at 77 F. is blended with amajor proportion of an oxidized asphalt having a softening point of fromto 180 F., e.g. to F., and a needle penetration value at 77 F. of from20 to 75, e.g. 32 to '60, a composition is obtained which unexpectedlyhas softening points which are higher than either one of its components.The resulting product has softening points from to 210 and needlepenetration (at 77 F.) values of from 35 to 200. In many instances awire rope lubricant user will prefer to have relatively high penetrationvalues accompanying high softening point properties. The reason for thisis that the higher the penetration of the lubricant, the less dangerthere is of brittleness at low temperatures. However, in the event lowtemperature operations are not contemplated and therefore highpenetration values are not necessary, it is possible by proper selectionof components to obtain wire rope lubricants wit-h softening pointsabove 180 F. but with needle penetration values of from about 45 to 150.The significance of lower needle penetrations is that the lubricanttends to be less sticky and tacky and thus somewhat less likely to causestaining or dirtying. Thus, where a user has no concern with brittlenessand desires little staining or dirtying in operation, the lower needlepenetration value lubricants offer an advantage. The lubricants withrelatively low needle penetrations are very generally obtained by usingthe oxidized asphalts from the lower end of the penetration ranges offrom 20 to 75, that is, from about 20 to 45. Oxidized asphalts havingpenetration values above about 45 tend to combine with the petrolaturnto give lubricants which exhibit higher penetrations than would beexpected from the penetration values of the components.

It has been further discovered that the particular quant-ities disclosedabove are quite critical. When more than about 15 wt. percent of thepetrolatum is used the resulting composition has an undesirable grainyappearance and feel. This is due to the fact that the asphalt tends toprecipitate out or salt out of the petrolatum.

Oxidized asphalt is the product obtained by subjecting relatively highviscosity residual oil produced from vacuum distillation of asphalticcrude to air blowing at temperatures of from 400 to 500 F. The airblowing is continued until sufiicient asphaltenes have been produced inthe reaction mixture to result in the desired levels of softening pointand penetration. Oxidized asphalt is also commercially known as blownasphalt. The method of obtaining softening points is described inASTM-D- 36-26. The method of determining penetration values is describedin ASTMD52.

Petrolatums are usually solid at ambient temperature and contain bothsolid and liquid hydrocarbons. They may be considered as colloidalsystems in which the solid hydrocarbon components are the external phaseand the liquid components are the internal phase. The solid portion hastaken up the liquid phase resulting in an amorphous mass. Petrolatumsmay vary widely in physical characteristics depending on the source,method of extraction, and degree of refinement. Petrolatums for use inthe invention. are preferably obtained as an unrefined bottom residuumfrom the distillation of a mixture of petrolatums.

Although not necessary for many uses, it is contemplated that thecompositions of the invention can have incorporated therein rust andcorrosion preventive agents such as sorbitan monooleate or a neutralbarium dinonyl naphthalene sulfonate sold commercially as NA-SUL- BSN orthe like. NA-SUL-BSN consists of 50 wt. percent of a neutral bariumdinonyl naphthalene sulfonate of the type described in U.S. Patent No.2,764,548 and 50 wt. percent light mineral oil. In using such commercialblends formulated with a mineral oil, the final lubricant tends to havea higher penetration value than if the additive blend were not present.However, there is no appreciable change in softening point values. Theserust and corrosion preventive substances are preferably incorporated inthe lubricant in amounts ranging from about 0.5 to 10, e.g. 1 to 3, wt.percent. Extreme pressure agents can also be included in the compositionwhere heavy duty type applications are involved. Other conventionaladditives can also be used.

The invention is further illustrated by the following examples whichshow preferred techniques of carrying out the invention.

Example I Ninety wt. percent of an oxidized asphalt having a softeningpoint of 169 F. and a penetration at 77 F. of 55 was blended with wt.percent of a petrolatum having a softening point of 160 F. and apenetration of 93. The melting point of the petrolatum was 168 F. and ithad a. cone penetration value of 34 at 77 F. The two components weremixed together until a uniform, smooth appearing mixture was obtained.This mixture was then evaluated for softening points and needlepenetrations at 77 F. The softening point obtained was 203 F. ThePenetration value obtained Was 200.

Example II Ninety seven wt. percent of the Example I composition wasblended with 3 wt. percent of sorbitan monooleate. The resultingcomposition had physical properties similar to those of the Example Icomposition. The composition of Example II had a softening point of 202F. and a penetration of 77 F. of 265.

Example III Ninety seven wt. percent of the Example I composition wasblended with 3 wt. percent of the NA-SUL-BSN al ready described. Theresulting composition had a softening point of 190 F. and a penetrationat 77 F. of 297.

In order to evaluate the rust preventive characteristics and resistanceto removal of the lubricant from the wire by the action of the elementsthe following test was carried out. Four segments of steel wire ropewere coated with the following materials: the composition of Example I,the composition of Example II, the composition of Example III and theoxidized asphalt used in preparing Examples I, II and III. The coatedsegments of wire rope were then placed in a completely exposed area on aroof of a three-storey building in Bayonne, New Jersey and left for aperiod of about eight months (ending January 18, 1961). At the end ofthis eight-month period these samples were removed from the roof andevaluated visually. An examination of wire rope segments followingremoval of the coating with propane revealed all specimens to .becompletely rust free and, therefore, fully protected throughout theduration of the test. It was known that oxidized asphalts provide abarrier against moisture penetration. The above tests demonstrate thatthe compositions of the invention provide an equally effective barrieragainst moisture penetration.

Example IV In order to evaluate the tendency of the composition toresist cracking and splitting at temperatures of about -30 F thefollowing tests were performed on the compositions of Examples I, II andIII. This test was carried out as follows: One-half inch wide, flatstrips of tin plate, 5 inches in length were coated on both sides withabout inch layer of each composition and allowed to remain at roomtemperature (75 F.) for approximately 24 hours. The coated strips werethen inserted in stoppered glass pour jars. The jars were placed in aconstant temperature cold bath maintained at -30 F. for 16 hours. Eachsample was then quickly withdrawn and immediately bent through around apipe of one inch diameter and the condition of the coating observed. Nocracking or peeling on bending at 30 F. was observed for any of thecoatings.

Example V In order to demonstrate the preparation of compositions havinghigh softening points with relatively low penetration values, Example 'Iwas repeated exactly except that the oxidized asphalt used had asoftening point of 168 F. and a penetration value of 36. The resultincomposition had a softening point of 180 and a penetra tion value of 45.All penetration values in the specific tion, unless otherwise indicated,refer to those obtained 2. A composition according to claim 1 whereinthe quanttiy of said petrolatum is from about 7 to 12 wt. percent.

3. A composition according to claim 1 wherein said petrolatum has asoftening point of from 140 to 175 F. and a needle penetration value offrom 80 to 100 at 77 F. and wherein said oxidized asphalt has asoftening point from 16 0 to 175 F. and a needle penetration value offrom 32 to 60 at 77 F.

4. A composition according to claim 1 wherein said oxidized asphalt hasa softening point of about 169 and a penetration of about 55 at 77 F.

5. A composition according to claim 1 wherein said petrolatum has asoftening point of about 160 F. and a needle penetration value of about93 at 77 F.

6. A method of lubricating wire rope which comprises applying thecomposition of claim 1 to said wire rope.

7. A composition comprising a major proportion of 5 a neutral barium'dinonyl naphthalene sulfonate.

References Cited in the file of this patent UNITED STATES PATENTSHoiberg Nov. 15, 1949 King et al. Sept. 25, 1956 OTHER REFERENCESLubrication of Industrial and Marine Machinery, by Forbes, John Wileyand Sons Inc., New York, 1943, pages 15 283 and 284.

Manufacture and Application of Lubricating Greases, by Boner, ReinholdPubl. Corp, 1954, New York, pages 111, 797499, and 921.

1. A COMPOSITION SUITABLE FOR USE AS A WIRE ROPE LUBRICANT COMPRISING 1TO 15 WT. PERCENT OF A PETRROLATUM HAVING A SOFTENING POINT OF FROM 120TO 175%F. AND A NEEDLE PENETRATION OF FROM 70 TO 120 AT 77%F. AND AMAJOR PROPORTION OF AN OXIDIZED ASPHALT HAVING A SOFTENING POINT OF FROM140 TO 180 AND A PENETRATION VALUE OF FROM 20 TO 75 AT 77*F.